A substrate processing apparatus is an apparatus configured to process the surface of a substrate such as a wafer or a liquid crystal substrate by supplying the substrate surface with a processing liquid (for example, an etching liquid, a rinsing liquid, or the like) in a manufacturing step for semiconductor devices, liquid crystal panels, or the like. Among such substrate processing apparatuses, an apparatus has been developed which is configured to perform a spinning process by supplying approximately the center of a substrate surface with a processing liquid from a nozzle while the substrate is being rotated horizontally, so that a centrifugal force of the rotation spreads the processing liquid over the substrate surface.
However, in the above-described substrate processing apparatus, if the processing liquid is discharged incompletely from the substrate surface, the processing liquid remaining on the substrate surface degrades the process uniformity (for example, process uniformity of an etching process, a rinsing process, or the like) on the substrate surface, or leaves stains such as smear or spot, thereby causing a process failure. Meanwhile, a processing liquid is excessively supplied in some cases, and consequently a large amount of the processing liquid is consumed. Hence, reductions in process failures and processing liquid consumption are demanded.